Anti-static cleanroom products and methods of making same

ABSTRACT

Anti-static cleanroom products having a coating of conductive polymeric particulates which decreases the surface resistivity of the products. Preferably, the particulates are pyrrole polymers. The anti-static properties are achieved by depositing conductive polymer particles onto the non-conductive substrate surface. The anti-static products include cleanroom wipers, stationery products (notebooks and writing instruments), garments and swabs (polyurethane foam tipped). The cleanroom stationery products include notebooks comprising polyethylene impregnated with silica. The invention also includes anti-static plastic gloves.

This application is a continuation of U.S. application Ser. No.08/616,249, filed Mar. 15, 1996, now U.S. Pat. No. 5,736,469.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to the prevention of particulatecontamination and static-discharge in cleanrooms. More specifically,this invention relates to anti-static products used in “cleanrooms”,semiconductor fabrication plants, pharmaceutical manufacturingfacilities, and other applications and environments where extremecleanliness must be maintained, and to methods for making such products.

2. Description of the Related Art

Cleanrooms are being used more often in a greater variety of areas. Therequirements for maintaining cleanliness in semiconductor fabricationcleanrooms, pharmaceutical manufacturing facilities and similarfacilities, for example, are stringent. Products brought into and usedin cleanroom environments must be carefully designed and manufactured toavoid the risk of contamination. In semiconductor fabricationcleanrooms, for example, surfaces frequently must be wiped withexceptionally clean wipers and cleaning solution in order to preventcontamination. Other examples of cleanroom products include clothing,gloves and stationery products (i.e., notebooks and writinginstruments).

It is well known that particulates can be brought into the cleanroomenvironment by workers themselves and by the materials which they use.In this regard, items which are subject to abrasion or wear are a causeof special concern since such abrasion and wear can result in particleformation. Cleanrooms are characterized by a special emphasis on theprevention of particulate generation and the removal thereof prior todeposition on cleanroom surfaces and products.

The term “applicator” or “wiper”, as used in this specification, isintended to mean a cleaning fabric suitable for use in cleaning surfacesin cleanrooms and the like. Such applicators or wipers are distinguishedfrom tissues and similar materials in that they are extremely clean andhave a relatively high degree of wet strength and structural integrity.Accordingly, these products do not disintegrate when used to wipesurfaces, even when dampened or saturated with cleaning liquids.

Cleanroom products used in sensitive areas, such as semiconductorfabrication cleanrooms and pharmaceutical manufacturing facilities, arecarefully selected for characteristics such as particle emission levels,levels of ionic contaminants, adsorptiveness, resistance to attack ordegradation by wear or exposure to cleaning materials, and lack ofattack by or degradation by biocides.

The contamination which is to be controlled is often called“microcontamination” because it consists of small physical contaminants,such as particulate matter of a size between that of bacteria andviruses, and chemical contaminants in very low concentrations, typicallymeasured in parts per million or parts per billion.

The contaminants usually are of three types including (1) particles, (2)ions and (3) “extractables”, which are impurities leached from thefibers of the wiper, for example.

Loose particles 100 micrometers and smaller in size are an anathema toobtaining high production yields and reliable semiconductor devices.Therefore, wipers, cleaning materials and other products used incleanrooms should emit as small a number of loose particles as possible.Similarly, ions and “extractables” are to be minimized since eachinterferes with the exacting process of semiconductor manufacturing.

Such requirements have been met by the provision of specially fabricatedproducts designed to emit very few loose particles or ions, whilemaintaining structural integrity when used. For example, cleanroomwipers that are wetted with cleaning solution and used to wipe thesurfaces to be cleaned.

Various cleanroom products have been developed for use in cleanroomenvironments. See, for example, U.S. Pat. No. 4,888,229 to Paley et al.;U.S. Pat. No. 5,229,181 to Daiber et al.; and U.S. Pat. No. 5,271,995 toPaley. The disclosures of those patents hereby are incorporated hereinby reference.

However, in some cleanroom environments, not only is it necessary tomaintain a “clean” environment, it is often also necessary to preventstatic discharge. The problem of static electricity has become an everincreasing problem where, for example, sensitive electronic equipment isbeing manufactured. Basically, static is created when two similarmaterials are rubbed together and then separated. One object tends togive up electrons whereas the other tends to accumulate them, therebyleaving the former with a positive static charge and the latter with anegative charge. When oppositely charged objects contact each other, astatic shock is created which corrects the imbalance.

Control of static electricity can be critical in many industrial orcommercial settings where an undesired electrostatic discharge (ESD) orspark can result in serious damage. For example, in explosiveenvironments such as in grain elevators or in flammable environmentssuch as an oil drilling rig or refinery, a spark can be extremelydangerous. In addition, static discharge can damage sensitive integratedcircuits. Therefore, such circuits must be safeguarded during theirmanufacture.

One particularly significant problem is the fact that the average personwill not sense a discharge of less than 3500 volts. Since manyelectronic devices can be damaged by potentials far lower than 3500volts, such devices can be damaged unknowingly and incorporated into thefinal product. As a result, the final product will be defective, withoutanyone knowing it.

Insulating materials can often be a source of static discharge,particularly those having a relatively high value of surface resistanceon the order of 10¹⁶ Ω(Ohms). Such insulated materials should bemodified to reduce the risk of static discharge. In the past, this hasbeen accomplished by increasing the electrical conductivity of theproducts. Such an increase in conductivity allows the product todissipate the static electrical buildup.

Some prior anti-static cleanroom wipers have been made by incorporatingfibers having a higher degree of electrical conductivity. Certain typesof carbon and metal fibers are inherently conductive, and therefore theincorporation of such fibers increases the conductivity of the textilematerial so that the previously static materials can be rendered staticdissipative. U.S. Pat. No. 5,324,579 to Sassa et al. discloses anon-woven textile material made useful for dissipating static electriccharges by incorporating an electrically conductive fiber.

However, the use of such fibers has many disadvantages. For example, theconductive fibers only allow for increasing conductivity in thedirection of the fiber. Accordingly, the resultant product would havedifferent conductivities in different areas and in different directions.Furthermore, conductive fibers may be relatively brittle when comparedto the majority of fibers used in a wiper product and therefore have atendency to break when flexed. Such breakage not only results in areduction in the static dissipative capability of the material, but alsoprovides a source of contamination to the cleanroom environment.

OBJECTS OF THE INVENTION

It is an object of the present invention to solve or alleviate theforegoing problems.

Accordingly, it is an object of the invention to produce cleanroomproducts, particularly cleanroom wipers, that can dissipateelectrostatic discharge while maintaining suitability for use incleanroom environments.

In particular, it is an object to provide cleanroom products such aswipers which have relatively uniform anti-static properties, withoutdegradation of the cleanroom quality of the products.

It is a further object of the present invention to provide suchcleanroom products and manufacturing methods which are relatively simpleand inexpensive to make and use.

The foregoing and other objects and advantages of the invention will beset forth in or apparent from the following description and drawings.

SUMMARY OF THE INVENTION

In accordance with the invention, cleanroom products are provided with acoating of conductive polymeric particulates. The particulates decreasethe surface resistivity of the products to give them anti-staticcharacteristics, without degrading the cleanroom properties of theproducts.

Preferably, the particulates are pyrrole polymers. The anti-staticproperties are achieved by depositing conductive polymer particles ontothe non-conductive substrate surface. Preferably the coating consists ofparticles spaced relatively widely from one another, covering less than75% of the area of the surface to which they adhere.

The anti-static cleanroom products include wipers, stationery products(notebooks and pens), garments, and swabs (i.e., polyurethane foamtipped swabs). The cleanroom stationery products also include notebookscomprising polyethylene impregnated with silica. The garments includeanti-static plastic gloves.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a scanning electron micrograph (“SEM”) of untreated nylonfibers.

FIG. 2 depicts a SEM of nylon fibers coated with pyrrole polymerparticulates.

FIG. 3 depicts a SEM of untreated polyester fibers.

FIG. 4 depicts a SEM of polyester fibers coated with pyrrole polymerparticulates.

DESCRIPTION OF PREFERRED EMBODIMENTS

The presently disclosed anti-static cleanroom products provide for thedissipation of static electric charge without degrading their cleanroomqualities. This is achieved by applying conductive polymer particulatesonto the insulative surface of the product. Surprisingly, the conductiveparticulate polymeric coatings, even though in particulate form, do notdegrade the cleanroom properties. It has been discovered that suchparticulates can be formed on the cleanroom product and are not easilyremoved. Accordingly, such coatings do not provide a significant sourceof “loose particle” contamination.

Additionally, it has been found that the particulate coating, eventhough not covering the entire product with either a uniform or coherentfilm, provides for increased dissipative qualities. A continuous andcoherent coating of the particulates is not required and is, in fact,avoided using the present invention. Furthermore, it has been found thatthe coating results in relatively uniform surface resistivities inmultiple directions.

The anti-static properties for the wiper are achieved by depositingconductive polymer particles onto the non-conductive fibers that make upthe wiper. The polymer particles decrease the resistivity of the wiperfrom approximately 10¹⁴ Ω to approximately 10⁸ Ω ohms per square cm.Preferably, the resistivity of the final product is from 10⁵ to 10¹¹ Ω.If the resistivity is greater than 10¹² Ω there will be no chargedissipation. However, if the resistivity is too low (i.e., the wiper istoo conductive) harmful sparks can result between a surface and thewiper. Therefore, it is important that the resistivity of the resultantwiper is between about 10⁵ to 10¹¹ Ω.

The wiper product is made, for example, by contacting an untreated wiperwith an aqueous solution containing polymerizable monomers, an oxidizingagent and a counter ion. Suitable monomers include aniline and pyrrole.The monomer is preferably pyrrole. Suitable oxidizing agents includeferric chloride and potassium persulfate. Suitable counter ions include2,6-Napthalenedisulfonic acid, disodium salt and benzenesulfonic acid,sodium salt.

According to one embodiment of the invention, an ESD dissipative wiperis prepared by adding a counter ion and an oxidizing agent in an aqueoussolution at room temperature and mixing. Subsequently, a monomersolution is added to the mixture and mixed. After sufficient mixing,uncoated cleanroom wipers are added to the solution and mixed. Thewipers are subsequently removed, rinsed and dried to result inanti-static cleanroom wipers.

The time for treatment can range from about 0.5 hour to about 2 hours,preferably about 1 hour to about 1.75 hours. The time of treatment canbe varied to an even greater extent, for example, by varying theconcentration of reactants in solution, the amount of wipers added tothe solution, the temperature of reaction and the amount of agitation.

The temperature of treatment is preferably room temperature, although itcan be varied if necessary. The concentration of the oxidizing agent,counter ion, monomer and uncoated product in the mixing solution canalso be varied and adjusted by one skilled in the art without undueexperimentation to result is a varying degree of resultant conductivityfor the product.

The resultant cleanroom product has irregular and non-uniform polymericparticles deposited onto the surface. The polymeric particles aredeposited onto the substrate to form an irregular coating. Preferably,the particulate coating covers less than 75% of the substrate surface,more preferably less than 50%, even more preferably less than 25% andmost preferably less than 10%. The embodiments of the invention includeapplying such coatings of conductive polymer particulates to cleanroomwipers, gloves and garments. Additionally, the invention includesapplying such particulates to plastic gloves.

What is particularly surprising in the cleanroom wiper and the othercleanroom applications is that the effect of these particles issufficient to decrease the resistivity of the product enough to providethe anti-static properties. This is the case even though the particulatecoating is non-uniform. Also surprising is the discovery that theparticulates adhere strongly to the substrates so they do notdetrimentally reduce the “cleanroom” properties of the products bybecoming dislodged upon exposure to cleaning solvents and/or during use.The particles are not dislodged in any significant amount, even bywashing the wiper.

Preferably, the particle counts of the resultant anti-static cleanroomproduct is less than 30 million per square meter, more preferably lessthan 20 million, even more preferably less than 15 million and mostpreferably less than 10 million.

Preferably, the non-volatile residue in deionized water is less than0.50 g/meter², more preferably less than 0.25 g/meter², even morepreferably less than 0.15 g/meter² and most preferably less than 0.10g/meter². Preferably the ion concentration is less than 20 ppm, morepreferably less than 10 ppm, even more preferably less than 5 ppm, andmost preferably less than 1 ppm.

Some of the wiper fabrics which have been successfully used in suchcleanroom applications and may be rendered anti-static include knitted,woven and non-woven fabrics such as the following:

1. 100% polyester or nylon, preferably knitted from continuous filamentyarn. Typical products are sold under the trademarks “AlphaWipe”;“AlphaSorb”; and “Alpha10”; or “MiracleWipe” by the Texwipe Company,Upper Saddle River, N.J. Woven polyester or nylon fabrics also can beused.

Some of such fabrics are sealed along the edges, in the manner describedin U.S. Pat. No. 4,888,229.

2. 100% spun bond polypropylene. The fibers of these fabrics arearranged randomly and are bound together by heat or chemical action. Atypical product using this construction is sold under the trademark“PolySat” by the Texwipe Company.

3. 55% cellulose and 45% polyester fiber or 100% polyester boundtogether by hydroentanglement. A typical product is the Texwipe“TechniCloth” product.

4. 100% polyurethane foam.

5. Other fabrics made of rayon, acrylic, abaca, (e.g., “M-Wipe” wiperssold by Texwipe), hemp, cotton, etc.

EXAMPLES

The following examples are illustrative of some of the products andmethods of making the same falling within the scope of the presentinvention. They are, of course, not to be considered in any waylimitative of the invention. Numerous changes and modification can bemade with respect to the invention including the selection of the fibermaterials, solvents, monomers, oxidizing agents, doping agents, rangesof proportions, time and temperature during operation and the like.

Example 1

300 mL of deionized water was placed in a 1.5 L beaker. The beakerplaced on the platform of an orbital shaker running at a speed of 150rpm. 2.0 g of benzenesulfonic acid, sodium salt and 2.8 g of ferricchloride were slowly added into the beaker after both ingredients werepredissolved separately in 50 mL water. Immediately after the additions,0.5 g of neat pyrrole (non-diluted) was added dropwise into the beaker.While the shaker was still running, 12.2 g of polyester wiper materialwas added to the beaker. The total weight represented two 9″×9″sealed-edge double-knit wipers constructed from 100 percent continuousfilament textured polyester.

The reaction was run for two hours at room temperature. Initially thecolor of the white wipers changed to light yellow and then graduallychanged to grayish black. At this stage, the wipers were taken out fromthe beaker and placed in a separate clean beaker. The wipers were thenrinsed several times with deionized water containing a surfactant(Triton-X®) and left to dry overnight in a laminar flow cleanroomworkstation.

The resultant dried products were tested for resistivity. The surfaceresistivity of the coated dry wipers was reduced from an original 10⁺¹⁴Ω to 10⁺⁵ Ω in all directions when measured by a surface resistivitymeter obtained from Static Control Services. The tremendous reduction inresistivity suggested that the wipers acquired excellent electrostaticdischarge (ESD) dissipative properties.

Example 2

To determine the contamination characteristics of the electrostaticdischarge (ESD) dissipative wipers, additional wipers were producedusing procedures similar to Example 1 with the following changes:

The steps in Example 1 were repeated except that the reaction wasconducted in a clean stainless steel tray (size 11¾″×9½″×3¾″). Thecontamination characteristics such as particles, non-volatile residues,and ions, of the original wipers were determined by usual laboratorytest procedures prior to coating. After the coating treatment, the sameparameters were evaluated in order to determine the extent of anyincrease in contamination that may have occurred as a result of theprocess.

Accordingly, 800 mL of deionized water was placed in the steel tray. Thetray was placed on the platform of the orbital shaker and the shaker wasallowed to run at 150 rpm. Four grams of benzenesulfonic acid, sodiumsalt (predissolved in 100 mL water), five grams of ferric chloride(predissolved in 100 mL water), and, lastly, 1 mL of neat pyrrole wereconsecutively added into the tray containing the water. The pyrrole wasadded dropwise. Immediately after these additions, six pieces of 9″×9″polyester wipers and two pieces of 4″×4″ nylon wipers (total weight 37g), were gently draped on the surface of the solution. The shaker wasrun for 30 minutes, at which time both of the nylon wipers turnedgrayish black whereas the polyester wipers turned light gray.

The nylon wipers were taken out and placed in a beaker and rinsedseveral times with deionized water and surfactant solution (Triton-X®).Meanwhile, the polyester wipers were allowed to run for additional timefor a total of 2 hours, at which point, they turned grayish black. Thepolyester wipers were rinsed in the same manner as the nylon wipers.Both sets of wipers were dried overnight at room temperature by hangingthem in a cleanroom workstation. The resistivities of the dry wiperswere measured using the same procedure set forth in Example 1. Bothtypes of wipers had excellent ESD dissipative properties. The coatednylon wipers had a resistivity of 10⁺⁶ Ω and the polyester wipers hadresistivities from 10⁺⁸ Ω to 10⁺⁹ Ω. Before the application of thecoatings all of the wipers had resistivities ranging from 10⁺¹³ Ω to10⁺¹⁴ Ω (insulative).

Both wiper materials were tested for the particle release counts byusing a HIAC/ROYCO Liquid Particle Counter and by using the RP-4 testprocedure as recommended by the Institute of Environmental Sciences. Theparticle counts of the treated wipers were under 10 million per squaremeter and, hence, are suitable for cleanroom wiping applications.Non-Volatile Residue (NVR) was also determined in deionized water forboth types of wipers and the numbers recorded were found to be withinthe range for cleanroom applications (0.10 to 0.15 g/meter²). Ions suchas sodium and chloride were also determined by Atomic Absorption (AA)Spectroscopy and by Ion Specific Electrode (ISE), respectively. Thesodium concentration was in the range of 1 ppm and the concentration ofchloride was 26.5 ppm (high). The coated wipers were also tested bybeing placed in an aqueous solution or in isopropyl alcohol solution forseveral days to determine the strength of the particulate adhesion. Itwas found that the particulates adhered to the substrate even afterseveral days of exposure.

Example 2 provided three important findings. First, nylon material coatsmore rapidly than polyester in this process (in terms of time needed forthe application of the coating). Second, ferric chloride should beavoided as the oxidizing agent if chloride concentration is a concernsince it causes the higher chloride contamination in the product. Third,the resultant particulate coating adheres strongly to the fibers.

Example 3

The procedure of Example 2 was repeated except the contents of the steeltray as shown in Example 2 were changed as follows:

a. 900 mL deionized water

b. 0.5 g of 2,6-Napthalenedisulfonic acid, disodium salt as the dopingagent predissolved in 50 mL water

c. 0.5 g of Potassium persulfate as the oxidizing agent predissolved in50 mL water

d. 1 mL of neat pyrrole added dropwise

e. and 4 pieces of 9″×9″ nylon wipers.

The reaction was run at room temperature. The entire content of the traywas allowed to shake on an orbital shaker for 30 minutes. The resultantproducts were grayish black wipers. The wipers were taken out and rinsedseveral times with deionized water containing surfactants and allowed todry. The dried wipers were tested and found to be as clean as thoseprepared in Example 2, including a substantial reduction in chloridecontent. The resistivity was tested and determined to be in the range of10⁺⁶ Ω. The chloride content in these wipers was low and quantified byCapillary Ion Analysis (CIA) technique to be lower than 1 ppm.Accordingly, ferric chloride was replaced with potassium persulfate asthe oxidizing agent for all the subsequent runs.

Example 4

Samples of the products made in Example 3 were inspected in the ScanningElectron Microscope (SEM) to evaluate the degree of enhancement ofparticulate burden before and after coatings. The fibers in the uncoatednylon wipers appeared very clean (see FIG. 1). However, the coated nylonfibers showed extremely random irregular polymer particulatesdistributed over the surface of each fiber and in between fibers (seeFIG. 2). It was remarkably surprising that a uniform dissipativeproperty was obtained throughout the entire length of each wiperconsidering the fact that the coatings are actually random andnon-continuous. A similar non-uniform distribution of particles was alsoseen in the case of the polyester fibers (FIG. 4). The uncoatedpolyester fibers also appeared very clean (FIG. 3). Interestingly, theoverall macroscopic appearance of the coated surface was very uniform.Accordingly, aesthetics were nicely maintained in the process in spiteof an extremely random microscopic distribution of the coatingparticulates.

Another surprising observation was the fact that although theparticulate distribution on the fibers was very non-uniform, the overallcoatings were tested and determined to be quite substantive (i.e.,adhered strongly to the surface of the fibers). The substantive natureof the coating is a primary factor in these products being suitable foruse in cleanroom applications. No particle shedding was observed duringactual wiping applications.

Example 5

In this example, thiophen was used for the coating. 950 mL of deionizedwater was added to a clean steel tray. In two separate beakers, 0.75 gof 2,6-Naphthalenedisulfonic acid, disodium salt and 0.60 g of potassiumpersulfate were each dissolved separately in 5 mL deionized water. Bothof these ingredients were subsequently slowly added to the water. Whilethe entire solution was being stirred in an orbital shaker, 30 drops ofmonomeric thiophen was added slowly. Four 9″×9″ pieces of nylon wiperswere placed in the solution and the entire contents stirred for morethan 4 hours at room temperature. Even after such an extended period ofoperation, the color of the wipers did not change at all. The wiperswere taken out, washed thoroughly and tested for ESD dissipativeproperties. No change in ESD dissipative property was noticed in thetreated fabrics. The resistivity reading was in the range of 10⁺¹⁴ Ω.The result appears to indicate that thiophen is an ineffective monomerfor this particular process under these operating conditions.

Example 6

ESD dissipative nylon wipers were prepared by adding the followingingredients together and running the reaction for 25 minutes at roomtemperature.

a. 600 mL deionized water in a clean steel tray

b. 1 g aniline hydrochloride

c. 2 mL concentrated hydrochloric acid

d. 2.5 g 2,6-Naphthalenedisulfonic acid, disodium salt, predissolved in5 ml water

e. 1.5 g potassium persulfate predissolved in 5 ml water; and

f. 4 pieces of 9″×9″ nylon wipers

After 25 minutes of orbital shaking, the color of the wipers changed todark green. The wipers were removed from the tray and rinsed well withdeionized water containing drops of a surfactant (Triton-X®).

The resistivity of the coated wipers was in the range of 10⁺⁸ Ω to 10⁺⁹Ω. Accordingly, aniline monomers are suitable for use in the process.

Example 7

A method for producing ESD dissipative wipers on a larger scale wasdeveloped using the experimentation as exemplified in Examples 1 through6. Experimental runs were carried out using the following procedures:

First, a paddle tank (capacity of 140 gallons) was cleaned with sodiumhydroxide solution. The tank was rinsed thoroughly with water.

Using a computer automation program, the following steps were conducted.

The tank was first filled with 140 gallons of water, the temperaturebeing maintained at 70° F. 270 g of 2,6-Naphthalenedisulfonic acid,disodium salt was first predissolved in one gallon of water taken outfrom the tank and subsequently added back into the tank. In anothervessel, 270 g of potassium persulfate was predissolved in one gallon ofwater (also taken out from the tank) and subsequently poured back intothe paddle tank. Both of the chemicals were allowed to mix well for 2minutes. 550 mL of neat pyrrole solution was then added directly to thetank and mixing continued for another 2 minutes.

Right after the completion of the addition and mixing of all thechemicals, 30 pounds total of nylon and polyester materials in the formof precut 9″×9″ wipers were added to the tank. The mixing was thenallowed to run at room temperature for 2 hours with the direction of themixing in the tank being changed every 2 minutes. The directional changeallowed for thorough mixing of the solution and the fabrics.

At the end of the treatment, all of the fabrics appeared dark grayishblack. The liquid was allowed to run out and the fabrics were rinsedthree times with a fresh supply of water. After rinsing, the wipers wereremoved using a basket and the excess water was extracted out by use ofa centrifuge. The wipers were then dried in a dryer at 100° F.

The surface resistivity of the coated nylon wipers changed from 10⁺¹⁴ Ωto 10⁺⁵ Ω, whereas resistivity obtained on the surface of the coatedpolyester wipers was in the range of 10⁺⁸ Ω to 10⁺¹⁰ Ω. From anaesthetic point of view, the surfaces of all the wipers appeared to beuniformly black. This example demonstrates the commercial production ofESD safe wipers by using the topical polymerization process.

Example 8

To determine the optimum time necessary for the production of ESDdissipative wipers, the above Example 7 was repeated using the samechemicals, water and materials in the same proportions. However, wipers,both nylon and polyester, were removed at different intervals of timeand examined to determine the extent of reduction in surfaceresistivities. In each case, two wipers, one polyester and one nylon,were taken out, washed in water and dried. In the case of the nylonwipers, the following results were obtained:

Time of Treatment Surface Resistivity Ω Remark 1 Hour 10⁺¹⁴ Insulative 1Hour 15 Minutes 10⁺¹⁴ Insulative 1 Hour 25 Minutes 10⁺¹¹ ESD Dissipative1 Hour 35 Minutes 10⁺⁸  ESD Dissipative

The polyester wipers were found to be in the range of 10⁺⁹ Ω to 10⁺¹⁰ Ωafter one hour 35 minutes of treatment time. Samples of polyester wiperstaken out 10 minutes earlier, were found to be in the range of 10⁺¹² Ω,hence still insulative. This confirms the earlier finding that polyesterwipers take longer to coat than nylon wipers.

This example demonstrates that under a set of operating conditions, thetime of treatment can be varied in order to achieve the desireddissipative range. The example also shows it is possible to provideproducts which are either very close to ESD dissipative (i.e.,resistivities <10⁺¹¹ Ω) or very close to being totally conductive (i.e.,having resistivities <10⁺⁴ Ω).

Cleanroom garments can be made using fabrics similar to those used formaking the cleanroom wipers. It is believed that the invention is alsouseful in creating anti-static plastic gloves, cleanroom stationeryproducts, cleanroom swabs and other cleanroom products.

The above description of the invention is intended to be illustrativeand not limiting. Various changes or modifications in the embodimentsdescribed may occur to those skilled in the art. These can be madewithout departing from the spirit or scope of the invention.

What is claimed is:
 1. An antistatic cleanroom product comprising acleanroom substrate material having a conductive particulate coating ona surface of the substrate to form said antistatic cleanroom product,wherein the substrate comprises polymeric fibers.
 2. The anti-staticcleanroom product as recited in claim 1, wherein said conductiveparticulate coating comprises conductive polymeric particulates.
 3. Theanti-static cleanroom product as recited in claim 2, wherein saidconductive polymeric particulates have an average size ranging from 0.01microns to 10 microns.
 4. The anti-static cleanroom product as recitedin claim 2, wherein said conductive particulate coating adheres to saidsurface when said surface is flexed.
 5. The anti-static cleanroomproduct as recited in claim 2, wherein said conductive particulatecoating covers less than 50% of said surface.
 6. An anti-staticcleanroom product as recited in claim 2, wherein said conductiveparticulate coating comprises pyrrole or aniline.
 7. The anti-staticcleanroom product as recited in claim 1, wherein said fibers form awiper product.
 8. The anti-static cleanroom product as recited in claim7, wherein said wiper product is knitted.
 9. The anti-static cleanroomproduct as recited in claim 7, wherein said wiper product is woven. 10.The anti-static cleanroom product as recited in claim 7, wherein saidfibers are arranged randomly to form said wiper.
 11. The anti-staticcleanroom product as recited in claim 1, wherein said fibers form agarment.
 12. The anti-static cleanroom product as recited in claim 1,wherein said fibers comprise nylon or polyester.
 13. The anti-staticcleanroom product as recited in claim 1, wherein said anti-staticcleanroom product has a surface resistivity between about 10⁵ to 10¹¹ Ω.14. The anti-static cleanroom product as recited in claim 1, whereinsaid cleanroom substrate material is a stationery product.
 15. Theanti-static cleanroom product as recited in claim 14, wherein saidstationery product is a writing utensil.
 16. The anti-static cleanroomproduct as recited in claim 14, wherein said stationery product is anotebook.
 17. The anti-static cleanroom product as recited in claim 14,wherein said notebook comprises polyethylene impregnated with silica.18. The anti-static cleanroom product as recited in claim 1, whereinsaid cleanroom substrate material is a plastic glove.
 19. Theanti-static cleanroom product as recited in claim 1, wherein saidcleanroom product substrate material is a swab.
 20. The anti-staticcleanroom product as recited in claim 19, wherein said swab comprises apolyurethane foam tip.
 21. The anti-static cleanroom product as recitedin claim 1, wherein the product has a particle count less than 30million per square meter.
 22. The anti-static product as recited inclaim 1, wherein the product has a non-volatile residue count less than0.5 g/m².
 23. The anti-static product as recited in claim 1, wherein theproduct has an ion concentration less than 20 parts per million.